Actual Contamination

This graphic illustrates a typical case for determining actual
contamination in an air pathway. Included in this illustration are the
following components:

Background Station. Sampling location used to determine the
background level for substances in observed release evaluations.

Source. Represents the source of the observed release of the
hazardous substance.

Station A. The sampling location of the air pathway from
which an observed release was documented.

Distance Rings. Represent areas of equal distance from the
source.

When an observed release has been demonstrated at Station A, all air
pathway targets located in the same distance ring as Station A as well
as any targets located in rings closer to the source, are considered
to be subject to actual contamination. It is important to note that
although the wind direction during sampling is important in
determining whether an observed release has occurred, it does not
otherwise affect the assessment of actual contamination.

At the Site Inspection (SI), does it make sense to put an air
sampling station on the outside portion of the distance ring?
ANSWER .